1. Field of the Invention
The present invention relates to a photosensitive composition.
A composition comprising a vinyl alcohol polymer, an ethylenically unsaturated compound which is radically polymerizable (hereafter referred to as "polymerizable monomer") and a photoinitiator is called a photosensitive composition and has been widely utilized, for example, as plate-making material for letterpress plate.
2. Description of the Prior Art
The above-mentioned photosensitive composition is exposed and developed, after it is prepared in a sheet form (referred to as "photosensitive resin plate") by providing it on a support such as a metal plate or a film plate, to form a resin relief. A photosensitive composition containing a vinyl alcohol polymer has been highly evaluated and widely used in the art of printing because its unhardened regions can easily be washed out with water after exposure and processing operations are easy (Published Examined Japanese Patent Application Nos. 39401/71 and 3041/75).
However, photosensitive compositions containing conventional vinyl alcohol polymers involve a serious drawback that even the vinyl alcohol polymers at hardened regions are removed upon removal of unhardened regions after exposure by washing with water, namely, upon development; for this reason, it is an actual situation that properties of resin relieves obtained are markedly injured.